• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.10a
• /
• pp.359-362
• /
• 2008

In this study, friction test was proposed to obtain coefficient of friction between tube and die in expansion zone of tube hydroforming and friction coefficients were evaluated at different materials, viscosity of lubricants and internal pressures. For this study, STKM11A and SUS tubes were prepared. The tube was expanded by an internal pressure against the tool wall. The tube was expanded by an internal pressure against the tool wall. By pushing the tube through the tool, a friction force at the contact surface between the tube and the tool occurs. From the measured geometries and FE analysis, the friction coefficients between tube and die at the expansion zone in tubular hydroforming can be estimated. The effects of the various internal pressures, viscosity of lubricants, tube materials and tube thickness on friction coefficients are discussed.

• Applied Microscopy
• /
• v.26 no.4
• /
• pp.401-410
• /
• 1996

The microwave fixator has recently been introduced in morphological research. The present study was carried out to investigate the ultrastructural effects of microwave fixation of rat brain. kidney, liver and skeletal muscle tissues. The results are as follows: In the case of microwave fixed cerebrum. the cytoplasmic processes of neurons and the various membranous organelles such as nuclear envelope, mitochondria, rough endoplasmic reticulum and Golgi apparatus were well preserved, The myelin sheath wrapping neuronal axon was prominent. Microwave fixed hepatocytes showed the microvilli on the free surface of bile canaliculus, the evident nucleolar components, and typical organelles. In nephron, ultrastructures of glomerulus and Bowman's capsule were preserved, and also tubular wall were structurally observed. Among the skeletal muscle cells, plentiful collagen fibers were appeared, myofibrils and mitochondria were typically observed. In conclusion, the microwave fixation procedures result in an good preservation of the tissues and would be time- and reagent-saving.

• Ocean Systems Engineering
• /
• v.5 no.4
• /
• pp.301-318
• /
• 2015

The present investigations introduce the shell-finite element discretization for the dynamics of slender marine pipelines. A long catenary pipeline, corresponding to a particular Steel Catenary Riser (SCR), is investigated under long-standing cyclic loading. The long structure is divided into smaller tubular parts which are discretized with 8-node planar shell elements. The transient analysis of each part is carried out by the implicit time integration scheme, within a Finite Elements (FE) solver. The time varying external loads and boundary conditions on each part are the results of a prior solution of an integrated line-dynamics model. The celebrated FE approximation can produce a more detailed stress distribution along the structural surface than the simplistic "line-dynamics" approach.

• Journal of Powder Materials
• /
• v.6 no.3
• /
• pp.238-245
• /
• 1999

The preparation of $n-TiO_2$ powder by the Chemical Vapor Synthesis process (CVS) was studied using the liquid metal organic precursor (TTIP). The residence time and the collection methods were considered as main processing variables through the experiments. The CVS equipment consisted of a micropump and a flashvaporizer, a tube furnace and a tubular collection device. The synthesis was performed at $1000^{\circ}C$ with various sets of collection zone. The residence time and the total system pressure were controlled in the range of 3~20 ms and 10 mbar, respectively. Nitrogen adsorption, X-ray diffraction and electron microscopy were used to determine particle size, specific surface area and crystallographic structure. The grain size of the as-prepared $n-TiO_2$ powder was in the range of 2~8 nm for all synthesis parameters and the powder exhibited only little agglomeration. The relationship between particle characteristics and the processing variables is reviewed based on simple growth model.

• Interaction and multiscale mechanics
• /
• v.3 no.4
• /
• pp.389-403
• /
• 2010

Based on the Model Coupled Method (MCM), a case study has been carried out on a Concrete-Filled Steel Tubular (CFST) tied arch bridge to investigate the vibration problem. The mathematical model assumed a finite element representation of the bridge together with beam, shell, and link elements, and the vehicle simulation employed a three dimensional linear vehicle model with seven independent degrees-of-freedom. A well-known power spectral density of road pavement profiles defined the road surface roughness for Perfect, Good and Poor roads respectively. In virtue of a home-code program, the dynamic interaction between the bridge and vehicle model was simulated, and the dynamic amplification factors were computed for displacement and internal force. The impact effects of the vehicle on different bridge members and the influencing factors were studied. Meanwhile the acceleration responses of some of the components were analyzed in the frequency domain. From the results some valuable conclusions have been drawn.

• Journal of Advanced Marine Engineering and Technology
• /
• v.29 no.6
• /
• pp.701-706
• /
• 2005

Pipes, tubes. and tubular sections with external transverse high fins have been used extensively for heating cooling, and degumidifying air and other gases. This work was performed to investigate an air side heat transfer charactieristics of minichannel with tension wound transverse fin. This estimate was confirmed conversion heat capacity the air side surface area enlargement and heat transfer charactieristics performed available inlet tube side hot water mass flux or outlet tube side air frontal air velocity. The most suitable tension wound transverse finned minichannel was measured extremely low in air side pressure drop and fin effectiveness $3.3\~4.4$. The pressure drop $0.9\~2.8Pa$ was ranged frontal air velocity $0.5\~1.2m/s$. It is also appeared that heat transfer in air side could be better conversion heat area which has been increased $330\%$ of heat capacity compared with the bare tube.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.03a
• /
• pp.273-280
• /
• 1997

Rotary swaging is a process for reducing the cross-sectional area or changing the shape of bar, tube or wires by repeated radial blows with one or more parirs of opposed dies. The present study is concerned with investigation the effect of process parameters upon product quality(hardness, roughness, precision of dimension). To enhance the product quality, experimental works are carried out for some process parameters such as forming speed, billet shape, lubrication, reduction of area and ratio of t/D. Rod shift formed by RSM25 under cold conditions has good surface quality, hardness and precision of dimension. The recommendable process conditions are suggested for solid and tubular products.

• Korean Journal of Ichthyology
• /
• v.4 no.2
• /
• pp.26-30
• /
• 1992

A stargazer fish, Uranoscopus tosae of family Uranoscopidae was collected for the first time in Kunsan, Korea. The U. tosae was similar to U. oligolepis in exomorphological features but had sharply distinguishable from U. oligolepis in the several characteristics, U. tosae had the embedded cycloid scales on the nape between both lateral lines. 4 preopercular spines, anterior tubular and posterior slit of nostril pores, and narrower and longer respiratory valve than orbit. No other patterns were presented on the surface of head and body.

• Textile Coloration and Finishing
• /
• v.7 no.2
• /
• pp.55-62
• /
• 1995

Plasma polymerization of Perfiuoropropene(PFP) and n-Hexane was carried out in a tubular type reactor by means of 13.56MHz radio frequency generator at the fixed RF discharge power of 25W and at the pressures of 100mTorr, 140mTorr and 200mTorr. The thin films were deposited on PAN fabrics in order to improve the dimemsional stability of woven states in hot water laundry. IR spectroscopy was used for the analysis of the structures of the thin films deposited and SEM for examination of surfaces of the fabrics. the PAN fabrics, which were coated by thin films at several experimental conditions, were immersed in boiling water for 2 hours and then the dimension stability of woven states were evaluated. In spite of very thin films, the results of surface modification were satisfactory. In general the performace of thin films by PFP was superior to that of n-Hexane.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.332-332
• /
• 2011

The adsorption and desoprtion properties on Pt(111) of chiral molecules, propylene oxide (PO) and 1,3-dimethyl butylamine (DMBA), have be characterized in utrahigh vacuum. Precision-doses of PO and DMBA onto a Pt(111) surface at 90 K have been achieved with a directed tubular molecular doser controlled by a micron-sized orifice and the reservoir gas pressure. Temperature-programmed desorption (TPD) mass spectra have been employed together with low-energy electron diffraction (LEED) analyses. In addition to the separate adsorption behaviors of PO and DMBA, the enantioselective adsorption of R- and S-PO on Pt(111) precovered with R- or S-DMBA have been investigated thoroughly, and the results will be presented.